Non-linear Transformer Model for Transients and Simulations During Transformer Energization

A. Tokic and I. Kapetanovic (Bosnia and Herzegovina), and J.A. Dias Pinto (Portugal)


Stiff differential equations, Stoer rule, inrush current, temporary overvoltages, metal-oxide surge arresters


A non-linear transformer model in transient process is proposed in this paper and can be used successfully in relatively low frequency cases. A non-linear magnetization curve is presented with a finite number of linear regions. “Stiff” differential equations, which described a condition of electrical circuit during the transformer energization, are solved by semi implicit Stoer rule. Sufficient number of regions for an accurate approximation of the magnetization curve in a transient are considered. Also, the most inconvenient transformer switching-in moments are determined. It was shown that temporary overvoltages originated during the transformer energization, may significantly affect metal-oxide surge arresters. Since the electric power system of Bosnia and Herzegovina is really weak, there is a possibility for appearing overvoltages which were mentioned above.

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